题解 | #每个题目和每份试卷被作答的人数和次数#

select *
        from
        (
        select
            exam_id as tid
            ,count(distinct uid) as uv
            ,count(1) as pv
        from exam_record
        group by exam_id
        order by uv desc,pv desc
        ) m

        union all 
        
        select *
        from(
        select
            question_id as tid
            ,count(distinct uid) as uv
            ,count(1) as pv
        from practice_record
        group by question_id
        order by uv desc,pv desc
        ) k